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Technical Support Document

Definition of important terms used in this document:

1) Designated “unclassifiable” – an area where EPA could not determine if there was a 

violation of the 2008 Lead national ambient air quality standard (NAAQS) or a contribution to a 

violation in a nearby area, because there was insufficient air quality data for both 2006-2008 and

2007-2009 and where additional monitoring data for 2010 could not result in a different 

designation.

2) Designated “attainment” – an area which EPA has determined, based on the most recent 3 

years of certified air quality data from 2006-2008 or 2007-2009, has no violations of the 2008 

Lead NAAQS during 36 consecutive valid 3-month site means; and which EPA has further 

determined does not contribute to a violation of the 2008 Lead NAAQS in a nearby area and that 

additional monitoring data from 2010 could not result in a different designation.

3) Designated nonattainment area – an area which EPA has determined, based on a State 

recommendation and/or on the technical analysis included in this document, has a violation of 

the 2008 Lead NAAQS during the most recent three consecutive years of quality-assured, 

certified air quality data. 

4) Prior nonattainment area – an area that is currently designated as nonattainment or 

maintenance for the 1978 Lead NAAQS (including both current nonattainment areas and 

maintenance areas).

5) Recommended nonattainment area – an area a State or Tribe has recommended to EPA be 

designated as nonattainment.

6) Violating monitor – an ambient air monitor whose design value exceeds 0.15 micrograms per 

cubic meter (μg/m3). As described in Appendix R of part 50, a violation can be based on either 

lead-total suspended particles (Pb-TSP) or Pb-PM10 data and only three months of data are 

necessary to produce a valid violating design value. 

7) 1978 Lead NAAQS – 1.5 μg/m3, National Ambient Air Quality Standard for lead

promulgated in 1978. Based on Pb-TSP indicator and averaged over a calendar quarter.

8) 2008 Lead NAAQS - 0.15 μg/m3, National Ambient Air Quality Standard for lead

promulgated in 2008. Based on Pb-TSP indicator and a three-month rolling average. Pb-PM10

data may be used in limited instances, including to show nonattainment.
2

Alabama

Area Designations For the 

2008 Lead National Ambient Air Quality Standards

EPA has revised the level of the primary (health-based) standard from 1.5 micrograms per cubic 

meter (μg/m3) to 0.15 μg/m3 measured as total suspended particles (TSP). EPA has revised the 

secondary (welfare-based) standard to be identical in all respects to the primary standard.

Pursuant to section 107(d) of the Clean Air Act, EPA must designate as “nonattainment”

those areas that violate the national ambient air quality standard (NAAQS) and those 

nearby areas that contribute to violations. The table below identifies the counties or portions 

of counties (or tribal areas) in Alabama that EPA is designating “nonattainment” for the 2008

lead national ambient air quality standard (2008 Lead NAAQS).

Table 1: Area Designation

Area (listed 

alphabetically)

Alabama

Recommended 

Nonattainment 

Counties

EPA’s Designated 

Nonattainment 

Counties

Nonattainment 

area for 1978 Lead

NAAQS

Troy, Alabama None1Pike (partial) No

Technical analysis for Troy

Introduction 

This technical analysis for the Troy Area identifies the partial county with a monitor that violates

the 2008 Lead NAAQS for contributions to lead concentrations in the area. EPA has evaluated 

Troy, Alabama based on the weight of evidence of the following factors recommended in 

previous EPA guidance: 

 Air quality in potentially included versus excluded areas;

 Emissions and emissions-related data in areas potentially included versus excluded from 

the nonattainment area, including population data, growth rates and patterns and 

emissions controls;

 Meteorology (weather/transport patterns);

 Geography/topography (mountain ranges or other air basin boundaries);

 Jurisdictional boundaries (e.g., counties, air districts, reservations, etc.); and

 Any other relevant information submitted to or collected by EPA (e.g., modeling where 

done appropriately).

 

1

In Alabama’s October 26, 2009, revised letter of recommendation, the State requested a portion of Pike County, 

within a 0.8 mile (or 1.3 kilometers (km)) radius from a center point at latitude 31.78627106 and longitude 

85.97862228, which fully includes the Sanders Lead Facility, be designated as “unclassifiable.” However, if EPA 

determines this request to be unfeasible, Alabama requests for the portion of Pike County within a 0.8 mile (or 1.3 

km) radius from a center point at latitude 31.78627106 and longitude 85.97862228, which fully includes the Sanders 

Lead Facility, be designated as “nonattainment.” 
3

Figure 1: Pike County Area of Troy, Alabama

Figure 2: Troy, Alabama Area and Surrounding Counties
4

Figures 1 and 2 are maps of the area analyzed showing the location and design value of the air 

quality monitor in the area, the counties surrounding the violating air quality monitor, and the 

state’s recommended area to be designated. The violating monitor in the Troy Area is located in 

Pike County, in close proximity to Sanders Lead Company, shown in Figure 1.

The Troy Area was not designated nonattainment for the 1978 Lead NAAQS. For each revision 

to a NAAQS EPA is required to conduct a separate designation action, which may result in the 

same or a different nonattainment boundary.

On October 1, 2009, Alabama recommended that a portion of Pike County be designated as 

“nonattainment” for the 2008 Lead NAAQS based on air quality data from 2006-2008. Their 

recommendation was based on data from Federal Reference Method monitors located in the 

state, as well as their own analyses of the recommended factors and air quality modeling. 

Subsequently, on October 26, 2009, EPA received a revised letter of recommendation from 

Alabama with a request to designate a portion of Pike County as “unclassifiable.” 

Based on EPA's technical analysis described below, EPA is designating the entire portion of Pike 

County, Alabama, within a 0.8 mile (1.3 km) radius from a center point at latitude 31.78627106 

and longitude 85.97862228, which fully includes the Sanders Lead Facility, as nonattainment for 

the 2008 Lead NAAQS as the Troy nonattainment area, based upon currently available 

information. This county is listed above in Table 1.

Detailed Assessment

Air Quality Data

This factor considers the lead design values (in μg/m3) for the air quality monitor in Pike County

in the Troy Area, and the surrounding area based on data for the 2007-2009 period. A monitor’s 

design value indicates whether that monitor attains a specified air quality standard. The 2008 

Lead NAAQS are met at a monitoring site when the identified design value is valid and less than 

or equal to 0.15 μg/m3. A design value is only valid if minimum data completeness criteria are 

met. A lead design value that meets the NAAQS is generally considered valid if it encompasses 

36 consecutive valid 3-month site means (specifically for a 3-year calendar period and the two 

previous months). For this purpose, a 3-month site mean is valid if valid data were obtained for 

at least 75 percent of the scheduled monitoring days in the 3-month period. A lead design value 

that does not meet the NAAQS is considered valid if at least one 3-month mean that meets the 

same 75 percent requirement is above the NAAQS. That is, a site does not have to monitor for 

three full calendar years in order to have a valid violating design value; a site could monitor just 

three months and still produce a valid (violating) design value.

The 2008 Lead NAAQS design values for Pike County in the Troy Area are shown in Table 2.
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Table 2. Air Quality Data

County State 

Recommended

Nonattainment

Monitor Name Monitor Air 

Quality 

System ID

Monitor Location Lead Design 

Value, 

2006 - 2008

(μg/m3)

Lead Design 

Value, 

2007-2009

(μg/m3)

Pike 

County, 

AL

No2

011090003 Henderson Road 1.35 1.35

011090006 Henderson Road 0.5030.31

Monitors in Bold have the highest design value in the respective county.

Pike County shows two monitors violating the 2008 Lead NAAQS. Therefore some area in this 

County and possibly additional areas in surrounding counties must be designated nonattainment.

However, the absence of a violating monitor alone is not a sufficient reason to eliminate nearby 

counties as candidates for nonattainment status. Each area has been evaluated based on the 

weight of evidence of the eight factors and other relevant information.

The violating monitors located in Pike County are in close proximity to Sanders Lead Company, 

Sanders Road, Troy, Alabama. The monitoring objective, according to the EPA monitor locator, 

is to determine the highest concentration of lead. The emissions from Sanders Lead Company 

and other area lead emitters will be discussed in the corresponding section.

The State of Alabama provided similar information from these monitors in their October 2009 

letter. The State information is consistent with the data provided by EPA, although the reported 

results are slightly different because of different reporting periods used. In addition, Alabama 

provided data from monitors owned by Sanders Lead Company sited near this facility. These 

monitors (Anderson and Murphree) are at a slightly greater distance from the facility and located

to the southwest and northwest of the facility. The reported maximum rolling three month 

average lead concentrations from these sites are 0.31μg/m3and 0.19 μg/m3for the period from 

November 2005 to August 2009. These values are also in excess of the new lead NAAQS of 

0.15 μg/m3.

Emissions and Emissions-Related Data

Evidence of lead emissions sources surrounding a violating monitor are an important factor for 

determining whether a nearby area is contributing to a monitored violation. For this factor, EPA 

evaluated county level emission data for lead and population data.

 

2

In Alabama’s October 26, 2009, revised letter of recommendation, the State requested a portion of Pike County, 

within a 0.8 mile (or 1.3 km) radius from a center point at latitude 31.78627106 and longitude 85.97862228, which 

fully includes the Sanders Lead Facility, be designated as “unclassifiable.” However, Alabama mentioned in their 

letter that if EPA determines this request to be unfeasible, Alabama requests for the portion of Pike County within a 

0.8 mile (or 1.3 km) radius from a center point at latitude 31.78627106 and longitude 85.97862228, which fully 

includes the Sanders Lead Facility, be designated as “nonattainment.” Both monitors are within the state’s 

recommended boundaries.

3 This monitor ceased operation in August of 2007. The maximum 3-month rolling average was calculated using 

data for the three month periods ending from January 2006 through August 2007.
6

Emissions

Emissions data were derived from the 2005 National Emissions Inventory (NEI), version 2, 

which is the most up-to-date version of the national inventory available when these data were 

compiled for the designations process in 2009. See 

http://www.epa.gov/ttnchie1/net/2005inventory.html. EPA recognizes that for certain counties, 

emissions may have changed since 2005. For example, certain large sources of emissions in or 

near this area may have installed emission controls or otherwise significantly reduced emissions 

since 2005. Some States provided updated information on emissions and emission controls in 

their comments to EPA. Alabama provided emissions information for the Troy Area from the

2005 NEI, therefore EPA relied on the 2005 NEI emissions data. These data are provided in 

Table 3.

Table 3 shows total emissions of lead (given in tons per year (tpy)) for violating and potentially

contributing counties in the Troy Area with sources emitting (or anticipate to contribute) greater 

than 0.1 tpy of lead according to the 2005 NEI. 

There are approximately 20,000 airport facilities in the U.S. at which leaded aviation gasoline is 

consumed. To evaluate the potential impact of emissions at and near these facilities, EPA 

recommends that States use the draft 2008 NEI. 

Table 3. Lead Emissions

County Facility in State

Recommended 

Nonattainment

Area?

Facility Name Facility 

Location

Total Lead Emissions

(tpy)

Pike County No* Sanders Lead 

Company

100 Sanders 

Road, Troy

4.44

* In Alabama’s October 26, 2009, revised letter of recommendation, the State requested a 

portion of Pike County, within a 0.8 mile (or 1.3 km) radius from a center point at latitude 

31.78627106 and longitude 85.97862228, which fully includes the Sanders Lead Facility, be 

designated as “unclassifiable.” However, Alabama mentioned in their letter that if EPA 

determines this request to be unfeasible, Alabama requests for the portion of Pike County within 

a 0.8 mile (or 1.3 km) radius from a center point at latitude 31.78627106 and longitude 

85.97862228, which fully includes the Sanders Lead Facility, be designated as “nonattainment.” 

The facility is within the state’s recommended boundary.

According to the 2005 NEI data, Pike County has one source (Sanders Lead Company) emitting 

at or above 0.1 ton per year. There are no other stationary sources emitting greater than 0.1 tpy

located within Pike County, nor any major sources of lead in the counties surrounding Pike 

County.
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Table 4: Airport Facilities Using Leaded Aviation Gas in Pike County

City Facility Name Type 2008 draft 

NEI (tpy)

Distance to Violating 

Monitor (km)

Pike County Troy Municipal Airport 0.1 8.83

There is one airport facility with aircraft using leaded aviation gas in Pike County that emits at or 

above 0.1 ton per year. Troy Municipal Airport is located approximately 8.83 km from Sanders 

Lead Company. 

Population Data

Table 5 shows the 2008 population for each county in the area that was evaluated, as well as the 

population density for each county in that area. These data help assess the extent to which the 

concentration of human activities in the area and concentration of population-oriented 

commercial development may indicate emissions-based activity contributing to elevated ambient 

lead levels. This may include ambient lead contributions from activities that would disturb lead 

that has been deposited on the ground or on other surfaces. Reentrainment of historically

deposited lead is not reflected in the emissions inventory.

Table 5: Population Data

County State 

Recommended 

Nonattainment?

2008 

Population

2008

Population 

Density 

(pop/sq mi)

Population 

Change 

2000-2008

Population 

% Change 

2000-2008

Pike 

County

No430.381 45 647 2

[Source of data: U.S. Census Bureau estimates for 2008 

(http://www.census.gov/popest/datasets.html) and estimation of the area of U.S. Counties]

Growth rates and patterns 

Pike County shows a population change of two percent between 2000 and 2008. EPA has 

considered the population growth rate for this area and does not believe that it affects the 

boundary recommendation.

 

4

In Alabama’s October 26, 2009, revised letter of recommendation, the State requested a portion of Pike County, 

within a 0.8 mile (or 1.3 km) radius from a center point at latitude 31.78627106 and longitude 85.97862228, which 

fully includes the Sanders Lead Facility, be designated as “unclassifiable.” However, Alabama mentioned in their 

letter that if EPA determines this request to be unfeasible, Alabama requests for the portion of Pike County within a 

0.8 mile (or 1.3 km) radius from a center point at latitude 31.78627106 and longitude 85.97862228, which fully 

includes the Sanders Lead Facility, be designated as “nonattainment.” 
8

Emissions Controls

Under this factor, the existing level of control of emission sources is taken into consideration. 

The emissions data used by EPA in this technical analysis and provided in Table 3 represent 

emissions levels taking into account any control strategies implemented in the Troy area before 

2005 on stationary sources. As mentioned above, on October 26, 2009, EPA received a revised 

letter of recommendation from Alabama with a request to designate a portion of Pike County as 

“unclassifiable.” This letter stated that the Alabama Department of Environmental Management 

(ADEM) has met with the source in Pike County to discuss potential mitigation measures for 

achieving compliance with the new lead standard. According to Alabama’s letter, the source has 

shown willingness to enclose the processes at the facility in order to abate lead emissions. This 

method has proven successful when used at other similar facilities, and should greatly reduce 

ambient lead concentrations if implemented at Sanders Lead in Pike County, Alabama. 

Meteorology (weather/transport patterns)

For this factor, EPA considered data from National Weather Service (NWS) instruments and 

other meteorological monitoring sites in the area, usually associated with major airport operation. 

A three-dimensional bar chart shows the wind frequencies in eight directions, for the four 

seasons, based on thirty two years of historical data5for the Troy Area. These historical data 

may provide evidence of the potential for lead emissions sources located upwind of a violating 

monitor to contribute to ambient lead levels at the violating monitor location, in the season of the 

violation. 

 

5 This data was taken from 1960-1992 Solar and Meteorological Surface Observation Network information issued 

jointly by the U.S. Department of Commerce: National Climatic Data Center and the U.S. Department of Energy: 

National Renewable Energy Laboratory.
9

Figure 3: Pike County Historical Wind Direction Frequency

As seen in Figure 3 above, the predominant wind direction in the Winter season is originating 

from the West/Northwest (WNW), while in the Spring season it is from the South/Southwest 

(SSW), in the Summer it is from the East/Southeast (ESE), and in the Autumn it is from the 

East/Northeast (ENE), indicating that lead sources located in any direction from the monitoring 

site in Troy could influence the monitored ambient air concentrations during different time 

periods. 

For each air quality monitoring site, EPA also developed a “wind rose,” which provides 

information about how wind speed and direction are distributed at the NWS monitoring station 

during the 30-year time period. The “spokes” on the diagram indicate the frequency of winds 

blowing FROM a particular direction. The length of a spoke shows the amount of time (in 

percentage) that the wind blows from that direction. Each concentric doted-line circle on the 

diagram represents increasing frequencies as you move out from the center. The spokes also 

provide information about the speed of the winds blowing from that direction. Each spoke is 

broken into discrete frequency categories that are color-coded to indicate the percentage of time 

that wind speeds are within that category (e.g., for winds blowing from the East, approximately

three percent of the time the wind speeds are between 2.1 – 3.6 meters/second (m/s)). 
10

Figure 4: Troy Wind Rose; Montgomery Airport

Annual Wind Rose – 30 years (1961-1990)

Figure 4 provides an annual wind rose diagram for the Troy Area. The wind rose was generated 

from 30 years (1961-1990) of wind speed and wind direction data collected at the NWS 

meteorological monitoring station located at the Montgomery Airport (NWS Station No. 13895). 

This station has the most representative long-term record of wind data for area near 

Montgomery, including the lead monitoring site located in the Troy Area.

The Troy Area wind rose is consistent with the wind direction bar chart in Figure 3 above and 

indicates that the wind does not blow from a strongly predominant wind direction. The winds 

blow from each direction at least three percent of the time, and from most directions more than 

five percent of the time. The highest frequencies of winds are from due East (approx eight 

percent), due North (approx seven percent), and due South (approximately seven percent). The 

wind speeds also vary with no strongly predominate speed category either. However, more than 

50 percent of the time, the wind speeds are less than 3.6 m/s. It is also important to note that 

winds are classified as calm (less than 0.5 m/s) approximately 15 percent of the time. The wind 

rose indicates that lead sources located in any direction from the monitoring site in the Troy Area 
11

could influence the monitored ambient air concentrations during different time periods. Also, 

the higher frequency of low to moderate wind speeds would indicate that air emissions sources 

located closer to the monitor have a larger influence than those located more distant from the 

monitor. 

EPA considered this historical wind direction and wind speed data to show evidence of the 

potential transport patterns for lead emissions sources located upwind and/or in close proximity

to that of a violating monitor to contribute to ambient lead levels at the violating monitor.

Additionally, in evaluating the Alabama climatological data for 2007, the statewide temperatures 

for the year were above normal and the statewide precipitation for the year was much below 

normal (see attached charts). In fact, Alabama was ranked as the 3rd driest state for 2007 

according to the rankings from the National Oceanic and Atmospheric Administration. See the 

following figures for more detail. Alabama attributes the prolonged warm and dry weather that 

lasted throughout the year as a factor in elevating emissions from soils in 2007 and resulting in 

monitored lead concentrations for that time period that were higher than other years. 
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Alabama attributes the prolonged warm and dry weather that lasted throughout the year to 

exacerbate lead concentrations in the soil. As a result, monitored lead concentrations for that 

time period were higher than previous years. EPA’s evaluation of the monitoring data during 

and just after this period of time, revealed the highest level of monitored values. The highest 

value of all of the 3-month rolling average for the 2007-2009 period occurs in December of 2007 

at a level of 1.35 μg/m3. Other monitoring values in that time period include 1.07 μg/m3for the 

November 2007 3-month rolling average; 1.18 μg/m3for January 2008; 1.15 μg/m3for February

2008; 1.02 μg/m3for March 2008; and 1.05 μg/m3for April 2008. The 3-month rolling averages,

excluding the period of November 2007 through April 2008, range from 0.10 μg/m3to 0.78 

μg/m3. 

Geography/topography (mountain ranges or other air basin boundaries)

The geography/topography analysis evaluates the physical features of the land that might have an 

effect on the air shed and, therefore, on the distribution of lead over the Troy Area.

The Troy Area does not have any geographical or topographical barriers significantly limiting 

air-pollution transport within its air shed. Therefore, this factor did not play a significant role in 

determining the nonattainment boundary.
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Jurisdictional boundaries 

Existing jurisdictional boundaries may be helpful in articulating a boundary for purposes of 

nonattainment designations, and for purposes of carrying out the governmental responsibilities of 

planning for attainment of the lead NAAQS and implementing control measures. These existing

boundaries may include an existing nonattainment or maintenance area boundary, a county or 

township boundary, a metropolitan area boundary, an air management district, or an urban 

planning boundary established for coordinating business development or transportation activities.

The Troy Area does not have any jurisdictional boundaries that affect this analysis. Therefore, 

this factor did not play a significant role in determining the nonattainment boundary.

Other Relevant Information

EPA received additional information relevant to designating this area pertaining to modeling that 

was performed by the State of Alabama. The American Meteorological Society/Environmental 

Protection Agency Regulatory Model (AERMOD) modeling system was used in the lead 

designation boundary modeling. The AERSURFACE tool was also used to generate the surface 

characteristics. Only emission sources from Sanders Lead were modeled using Title V permit 

and facility data. However, other sources that may locally impact the state monitors were not 

modeled. These less than 0.1 tpy sources, which are all well within the State’s recommended 

boundary, include K W Plastics (a recycling facility), and reentrained lead emissions from a 

railroad and major roadway that borders the Sanders Lead facility.

Downwash was considered for all Sanders Lead stacks in the modeling. The AERMOD system 

was simulated twice, using both Montgomery NWS Airport site and the Sanders Lead facility

surface characteristics, since site specific meteorological data at Sanders Lead was unavailable. 

The model was simulated twice in this manner because the State conservatively decided to utilize 

the surface characteristics around both sites in all modeling and reported the highest 

concentrations between the two. 

As required by EPA modeling guidance in 40 CFR Part 51 Appendix W: Guideline on Air 

Quality Models, the State included five years (i.e., 2001-2005) of meteorological data. The

AMS/EPA Regulatory Model Terrain Pre-processor program inputs were developed with 

National Elevation Data. AERMOD was simulated using default modeling inputs. A 10 km by

10 km discrete Cartesian receptor grid was used in the modeling analysis with grid spacings of 

100 meters. The maximum 3-month rolling concentration of 0.779 μg/m

3 was modeled near the 

location of the Sanders Lead stacks. As mentioned above, excluding the November 2007 

through April 2008 time period, the monitored 3-month rolling concentrations ranged from from 

0.10 μg/m3to 0.78 μg/m3, which is in line with the modeled values. As noted above, Alabama 

attributes the highest design values to a period of time where there was unusually dry weather 

and many areas in the state were under drought conditions. Despite the fact that these sources

were not modeled from the facility, the southwest yellow contours shown in the following plots 

from the State modeling agree with design value of 0.19 μg/m3from the Sanders Lead-owned 

Murphee monitor. The modeling contours and the data from the second state monitor indicate 

that the lead concentrations rapidly decrease with distance from the industrial area, railroad and 
14

roadway such that predicted quarterly lead concentrations would be below the NAAQS (i.e., 

>0.15 μg/m3) well within the recommended boundary of 0.8 mile (or 1.3 km) radius from a 

center point at latitude 31.78627106 and longitude 85.97862228, which fully includes the 

Sanders Lead Facility. The maximum predicted concentration at the outer edge of the State’s 

recommended nonattainment boundary is less than 50 percent of the NAAQS (0.072 μg/m3.

EPA reviewed the modeling analysis included in Alabama’s demonstration. The results of that

review are summarized below:

Sanders Lead, Troy, Alabama – Pike County

AERMOD Modeling

1. Source characterization

a. If any fugitives, how were they characterized? No

b. Did stacks use defaults or actual parameters? Used data from Sanders Lead 

and considered downwash

c. What is the emissions year? There is no emissions year. The emissions used in 

the Sanders Lead Designation modeling performed by ADEM represent the 

allowable emissions for the units, not the actuals. This allows for additional 

conservatism in the modeling.

d. What is the source of the emissions (NEI or other)? Title V permit emissions

Emission rate 

(g/s)

X (meters) Y (meters) Base elev 

(meters)

Stack 

height 

(meters)

Stack 

Temp 

(K)

Stack 

exit vel 

(m/s)

Stack 

diameter 

(m)

STACK22 0.60000E-01 596668.6 3517149.0 162.0 54.86 366 36.27 1.20

STACK22 0.60000E-01 596701.9 3517158.2 161.2 54.86 366 36.27 1.20

STACK24A 0.30000E-01 596744.4 3517284.0 161.7 27.43 339 32.31 0.90

Stack24B 0.30000E-01 596648.4 3517188.2 161.2 27.43 339. 32.31 0.90

STACK27 0.20000E-01 596754.1 3517148.0 156.4 9.14 294. 18.29 1.10

e. Were actual emissions used or potential emissions - assumed potential 

emissions

f. Were multiple sources modeled or single source modeling done? Only emission 

sources from Sanders Lead were modeled.

2. Meterology

a. Years and stations used- 2001-2005 Montgomery (MGM) AL NWS (72226 

)(sfc); Alabaster (53823) (upper air)

b. Was meteorological data representative of source(s), temporally and spatially

(surface characteristics) - The AERMOD system was simulated twice using 

both Montgomery NWS Airport site and the Sanders Lead facility surface 

characteristics since site specific meteorological data at Sanders Lead was 

unavailable.

3. Receptor network
15

a. Adequate spatial coverage and adequate receptor spacing? A 10 km by 10 km 

discrete Cartesian receptor grid was used in the modeling analysis with grid 

spacing of 100 meters. 

b. Receptors placed in ambient air locations

c. Terrain included in modeling – Yes, terrain elevations generated using 

National Elevation Data.

4. Output

a. 3-month rolling average contours. Highest concentration located at on the facility

property.

b. 1

st highest modeled concentrations (μg/m3

)

Year Facility surface 

characteristics 

MGM NWS surface 

characteristics

2001 0.835 0.365

2002 0.705 0.416

2003 0.777 0.411

2004 1.079 0.5238

2005 0.976 0.396
16

Conclusion

After considering the factors described above, EPA has determined that it is appropriate to 

include the portion of Pike County as the Troy nonattainment area for the 2008 Lead NAAQS. 

This area is located within a 0.8 mile (or 1.3 km) radius from a center point at latitude 

31.78627106 and longitude 85.97862228, which fully includes the Sanders Lead Facility.

EPA is basing this nonattainment designation determination and boundary on the fact that Pike 

County contains two air quality monitors that show violations of the 2008 Lead NAAQS, based 

on 2007-2009 air quality data. Additionally, the Sanders Lead facility emits relatively large 

quantities of lead that EPA believes caused the violations of the lead NAAQS at those air quality

monitor for this period. Available modeling and monitoring data indicates that a boundary

within a 0.8 mile (or 1.3 km) radius from a center point at latitude 31.78627106 and longitude 

85.97862228, which fully includes the Sanders Lead Facility, is a sufficient distance to 

encompass the area that exceeds the lead NAAQS.
17

Based on its consideration of all the relevant, available information, as described above, EPA 

believes that the boundaries described herein encompass the entire area that does not meet (or 

that contributes to ambient air quality in a nearby area that does not meet) the 2008 Lead 

NAAQS.